For convenience, the following discussion of the present invention makes reference to egg rolls as comprising a typical comestible product assembled from the pastry leaves of the present invention. It will, however, be appreciated that any alternative pastry wrapped comestible products of generally cylindrical form are also contemplated, such as completely wrapped sausages, particularly cocktail sausages, fruit conserves, cheeses and the like which have been assembled into a generally cylindrical form approximating that of the filling of an egg roll.
Egg rolls are well know in the art and have been known for many years.
An egg roll is comprised of a generally cylindrical mass of a filling preparation, usually vegetable materials with the addition of fish, seafood, meat or cheese, and which has been suitably flavored by the addition of salt, flavor enhancers, spices and the like.
In the assembled form of the egg roll, the cylindrical mass of filling preparation is wrapped completely within a single leaf of an appropriately aged pastry material formed form a admixture of flour, water, salt, and if desired, egg white or whole egg.
In the formation of the leaves the admixed mass is extruded into ribbon-like form before aging of that material and is then passed through calendering rolls to produce a continuous sheet of pastry material, commonly of 24 inches width. Due to the manner in which it is formed, the grain of the sheet, i.e., its axis of maximum strength, extends longitudinally of the sheet.
The sheet is then cut into squares, commonly seven inch squares, and the cut sheets are then stacked to permit them to age and the gluten content coalesce in readiness for subsequent use of the leaves in the assembly of egg rolls. A dusting of corn starch is applied during the rolling process to prevent adhesion of the pastry material to the calendering rolls, and also to prevent adhesion between the cut sheets when stacked one upon the other.
Egg rolls of high quality must of necessity be assembled manually if lightness and delicacy of the pastry wrapping is to be preserved. Egg rolls can be produced by automated machinery capable of duplicating the various manual manipulations of a skilled manual assembler, but, only in the event that thicker and thus less delicate pastry leaves are employed.
Typically, a single leaf of the pastry material is placed on a flat surface with the grain of the leaf extending at 45 degrees to the direction of subsequent rolling of the egg roll. So doing orients one pair of opposed corners of the leaf in a longitudinal direction, and orients the other pair of opposed corners in a lateral direction.
A cylindrical mass of a prepared filling preparation is then placed on the pastry leaf with the axis of the cylindrical mass extending parallel to a line extending between the respective lateral corners. The adjacent longitudinal corner of the leaf is then folded over the filling preparation to envelop the axial cylindrical surface of the filling preparation, subsequent to which the lateral corners of the sheet are folded upwardly and over the partially formed egg roll to form end enclosures for the filling preparation.
It is at this point that a problem occurs in the assembly of an egg roll, and, one which presents major problems in the automated assembly of egg rolls. This is due to the fact that the lateral corners of the pastry leaf must be moved from their initial planar condition and conformed to a substantially that of a closed ended cylinder without rupturing or tearing of the leaf.
Rupturing or tearing of the leaf can have disastrous consequences during subsequent processing of the egg roll. Rupturers or tears, or, corners that are not completely closed, can permit the oil in which the assembled egg roll is subsequently fried to enter into the assembled egg roll and come into direct contact with the enveloped filling preparation. The oil typically is at a temperature of 450 degrees or higher. If it is allowed to contact the enveloped filling preparation, the hot oil will cause boiling of the moisture content of the filling preparation and the build-up of steam pressure within the egg roll. At the very best, contamination of the filling preparation with the frying oil will occur. The usual consequence is, however, that a sufficient build-up of steam pressure occurs within the egg roll to cause the explosion of the egg roll while within the mass of boiling oil. Such an occurrence is dangerous and highly undesirable. Not only can it cause spattering of the boiling oil, but also, it will cause contamination of the boiling oil with particles of the filling preparation. Ultimately, those particles become charred in the boiling oil and are deposited and form unpleasant discolorations on the other egg rolls in the batch being processed.
The formation of the first fold in the leaf for it to wrap around the axial cylindrical surface of the filling preparation poses no particular problem whether it be effected manually, or, effected by automated machinery. The reason is that a development of the cylindrical surface of the filling preparation results in a planar form. Thus, one shape is compatible with the other.
The problem arises when the subsequent side folds are to be made. Here, the dichotomy is that a planar sheet is being required to cover an end of a solid cylinder and also to conform to the axial cylindrical surface of that cylinder while producing a minimum of stresses in the leaf, and at the same time minimizing folds and unsightly bulges in the folded leaf. The problem is somewhat similar to that of inserting a cylindrical object into a conventional mailing envelope and then requiring the conventional mailing envelope to conform to the external cylindrical contour of the cylinder. The two shapes are incompatible by virtue of the differences in their geometry.
One alternative that suggests itself in overcoming this problem is to orient the cylinder of filling preparation with its axis parallel to a major edge of the wrapping leaf. This, however, would require pinching of the sheet at the ends of the cylinder of filling preparation subsequent to rolling of the leaf and would result in a product having a shape totally dissimilar to that of a conventional egg roll. Various other alternatives suggests themselves such as those employed in the formation of ravioli packets and the like. However, in each instance the resulting product would not have the appearance of a conventional egg roll.
The problem that arises in the formation of egg rolls, is that the geometry is such that the side folds do not automatically assume a position in which they extend perpendicular to the longitudinal axis of the filling preparations. Instead, the side folds will assume position during rolling of the egg roll in which they diverge one from the other relative to the axis of the filling preparation, i.e., they will splay outwardly. Unless this condition is corrected prior to rolling of the egg roll, it will result in overhangs and an unsightly appearance at the ends of the egg roll.
The reasons for this outward splaying lie in the geometry of the thusly folded leaf. An axis or longitudinal cross section through the filling preparation approximates a rectangle, and the leaf at this point has been folded into the shape of a hollow rectangular cylinder. If, now, the hollow rectangular cylinder is collapsed to planar form, as it will be in the subsequent rolling of the egg roll, then, the sides of the hollow rectangular cylinder will move outwardly by one half of the height of those sides.
An astute manual assembler can correct this problem during the hand-assembly of the egg roll by a re-orienting process of pinching the tucking-in of the leaf at the ends of the filling preparation, and by pulling back the folds between the longitudinal side folds and the lateral first fold. This, however, is a highly skilled operation that depends on the acuity and manual dexterity of the assembler, and is dominantly a matter of "feel" on the part of the assembler. These variables cannot be predicted with accuracy, and as a consequence, automated machinery has not been developed for duplicating the manual operations.
Heretofore, the assembly of egg rolls by automated machinery has only been accomplished by compromising the neatness and aesthetic appearance of the machine formed egg roll by purposely permitting the formation of unattractive overhangs at the ends of the egg roll. Additionally, the machine forming operation compromises the delectability of the formed egg roll by the need to employ relatively coarse leaves of a sufficient weight and strength to accommodate the increased stresses arising in the automated assembly process.
Typically, a skilled manual assembler of egg rolls working with a standard seven inch square leaf can produce a defect-free egg roll from leaves weighing as little as 16 leaves to the pound weight. In contradistinction, it is found that leaves weighing as much as 8-10 leaves to the pound weight must be used in an automated process in order to produce defect free egg rolls. This, however, results in a cardboardlike covering of machine assembled egg roll as opposed to a delectable, crisp and readily frangible covering produced by a skilled manual assembler. For this reason, machine assembled "frozen" egg rolls produced by automated machinery have met with less than favorable consumer acceptance in view of the tough, doughy and heavy texture of the covering leaf.